Continuous tendency drive arrangement



Jan. 24, 1967 J. 5. CHANDLER 3,299,724

CONTINUOUS TENDENCY DRIVE ARRANGEMENT Filed Oct. 9, 1964 JASPER s. CHANDLER INVENTOR A T TORNE YS United States Patent Office 3,299,724 CONTINUOUS TENDENCY DRIVE ARRANGEMENT Jasper S. Chandler, Rochester, N.Y., assignor to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey Filed Oct. 9, 1964, Ser. No. 402,809 8 Claims. (Cl. 74143) The present invention relates to a continuous tendency drive arrangement and more particularly to a vibratory motor arrangement suitable for energizing a winding and reeling equipment subject to continuous tension considerations.

Many tendency drive arrangements are now well known. Some take the form of a vibrator electric motor. These drive arrangements often utilize a single drive arm where by there is no driving coupling during at least a portion of its operation. Also because of the single drive arm, certain portions of its stroke tend to counteract the drive stroke and thus reduce the effectiveness of the drive.

Therefore, an object of the present invention is to provide an improved tendency drive arrangement.

In accordance with one embodiment of my invention a shaft to be driven has coupled thereto a drive disk peripherally engaged by a pair of drive shoes each pivotally mounted and mutually spring biased to drive the disk. The pivot mounting of these drive shoes is loosely fitted to all-ow the drive shoes to move laterally relative to the disk. A vibratory driving force is applied sequentially to the drive shoes in the region of the spring coupling by means of bifurcated rocker arm pivotable about a fulcrum such that the motion of the drive arm directly counteracts the spring bias and at the same time tends to move the drive shoes to a next increment of the drive disk. By such operation the drive shoes are at least partially disengaged respectively from the drive disk surface during this motion. In this manner the driving force of the spring is continuously applied to the disk by at least one drive shoe.

The subject matter which is regarded as my invention is particularly pointed out and distinctly claimed in a concluding portion of this specification. The invention, however, as to its organization and operation, together with further objects and advantages thereof, will best be understood by reference to the following description taken in connection with the accompanying drawing, in which:

FIG. 1 is a top plan View of one embodiment of my invention; and

FIG. 2 is a partial cross section view taken along the line 22 of FIG 1.

Referring now to the drawing wherein like reference numbers refer to similar parts, I have shown in FIG. 1 a shaft 10 coupled to a mechanism to be driven. For the purpose of the present discussion this mechanism may be visualized as a reel for winding tensioned film strips or the like. Such a mechanism continuously tends to unwind because of the film tension. Nonrotatably coupled to the shaft 10 by lock means such as a key 11 is a drive disk 12 engaged at its periphery by a pair of arcuate drive shoes 13 and 14. The drive shoes are what may be termed rigid as opposed to leaf springs and the like which are sometimes used as drive members of vibratory motors. The drive shoes are pivotally supported on hinge pins 16 and 17 respectively which are preferably located diametrically opposite the effective engagement point of the drive shoes 13 and 14. The slots 18 and 19 of the hinge pins 16 and 17 are substantially larger than the hinge pins, allowing limited radial motion of the pivot ends of the drive shoes 13 and 14 respectively. Thus the drive ends of the drive shoes may be lifted from the disk periphery as explained below. The drive shoes are maintained on 3,299,724 Patented Jan. 24, 1967 the hinge pins by caps 20 indicated in phantom. I prefer that the drive shoes be fabricated from a durable plastic such as a stabilized nylon. The disk 12 may be made of metal.

Tension of the drive shoes 13 and 14 relative to the drive disk 12 is maintained by a relatively compliant precalibrated spring 21 made of a material such as piano wire and coupled between the drive shoes at points spaced from the pivot pins 16 and 17 respectively. The spring 21 develops an outward driving force as indicated by the arrows 22 and 23. In the position shown, the spring force 23 causes a shoe force 24 to be applied to disk 12 and directed toward the attachment point of the spring at 23. The line of action of force 24 passes below the center of shaft 10 and therefore creates a right hand torque tending to produce rotation as shown by an arrow 31. The spring force directly controls the drive torque of the system. In one embodiment of my invention I prefer that the spring 21 be recessed in slots 25 in the drive shoes so that the overall thickness of this tendency drive arrangement may be reduced to a thickness of the order of A driving rocker arm 26 is pivoted about a fulcrum point 27 and is driven by an eccentric drive means 28 as indicated by a double-ended arrow 29. The vibratory drive being pivoted at the point 27 creates motion as indicated by the double-ended arrows 30 in the drive arms 32 and 33 of the rocker arm 26. This motion of arm 32 creates a force as indicated by an arrow 35 which is applied to the drive shoe 13 at a point 35a which is a slightly greater distance from fulcrum 16 than the spring force '22. The force 35 therefore largely counteracts the spring force 22, thus greatly reducing the contact force between shoe 13 and disk 12 and causing the shoe 13 to slide at a very low contact pressure to the left on disk 12 to return to its starting :position. An instant later, the rocker arm 33 creates a pressure, as indicated by an arrow 36, at a point 36a to overcome the spring bias on the drive shoe 14 and similarly return shoe 14 to its starting position while shoe 13 is operative in producing a right hand rotational torque (arrow 31). The points indicated as members 10, 35a, and 27 and 10, 36a, and 27 each form a right angle. Also the points 35a and 36a are each spaced from the pivot IPOIIIIS 16 and 17 a greater radial distance than the spring forces 22 and 23.

Thus it may be seen that as the rocker arm 26 vibrates, the drive shoes 13 and 14 are alternately returned to the same starting bite position. At each oscillation, each shoe produces a disk movement which is limited to the extent that the drive disk 12 is rotatable during each drive increment from zero up to a maximum determined by movement 30. When rotatable, the spring 21 will move the disk in a clockwise direction as indicated by the arrow 31. Also it should be noted that, if little or no disk motion has occurred between successive contacts of the rocker arm 26 against the drive shoes 13 and 14 respectively, only the amount of energy used by the disk is required from rocker arm 26 to restore the shoes to their starting position. Thus my invention is substantially more efficient than other motors of this general type wherein a full stroke is required even if no rotation obtains. Furthermore, it should be noted that the torque imparted to disk 12 is controlled solely by spring 21 and is not subject to change as is the friction, for example, of a slipping clutch.

In order to increase the friction of the drive, I prefer that the drive disk 12 be provided with a V-groove as indicated at 40 in FIG. 2. The drive arms as indicated by 13 are provided with a mating V-surface 41, for rolling contact action. The arm mating surfaces 41 are arcs whose centers are essentially at the pivot points 16 and 17 respectively. This V-gr-oove also maintains a proper elevation of the drive shoes 13 and 14 whereby they do not waste energy sliding on other support surfaces. The increased drive friction provided by the V-groove permits the direction of the shoe contact forces such as force 24 for shoe 14 to depart substantially from the radial direction to produce the driving torque without danger of slippage.

While I have shown a particular embodiment of this invention, modifications thereof will occur to those skilled in this art. I intend therefore to have the appended claims cover such embodiments as properly fall within the proper scope of the present invention.

1 claim:

1. A tendency drive arrangement comprising:

a drive disk;

a pair of arcuate drive shoes each positioned to produce selective rolling action against said disk and to have one end of each engage a separate portion of the surface of said disk;

means for pivotably supporting said pair;

spring means coupled between said pair at points spaced from said pivot support means to bias said pair against said disk and in a given tangential direction relative thereto, thereby to tend to rotate said disk in said given direction;

a bifurcated rocker arm drivable to engage each one of said pair sequentially to counteract the spring bias respectively and to move said one end thereof to a new position on said disk to the extent said disk has rotated since a last engagement of said rocker arm on said one; and

means for driving said arm in a vibrating motion.

2. A tendency drive arrangement as in claim 1 wherein said pivot means are each diametrically positioned relative to the engagement respectively of said shoes on said disk.

3. A tendency drive arrangement as in claim 1 wherein said drive shoes are rigid and said pivot means each provide a loose fit so that the entire drive shoe is moved during reaction to engagement by said rocker arm.

4. A tendency drive arrangement for a mechanism subject to continuous tension considerations, comprising:

a drive disk coupled to drive the mechanism;

a pair of arcuate drive shoes positioned to have one end of each engage a separate portion of a peripheral surface of said disk to produce thereon selectively a rolling action;

means for pivotably supporting said pair, said means providing a loose fit so that the contact between said pair and said disk may be disengaged by outward radial movement of said one end of each respectively;

spring means coupled between said pair at points spaced from said pivot support means to bias said one end respectively to engage said disk and to provide torque to rotate said disk in a given direction; and

a vibratory driving means arranged to engage each one of said pair sequentially to counteract the spring bias respectively and drive said one to move it to a new position on said disk to the extent said disk has rotated since a last engagement of said driving means on said one.

5. A tendency drive arrangement as in claim 4 wherein said pivot means are each diametrically positioned relative to the engagement respectively of said shoes on said disk.

6. A tendency drive arrangement as in claim 5 wherein each of said pair partially surrounds said disk so that said spring bias acts generally away from said disk and said drive applies force generally toward said disk to thereby lift said one end from said disk during repositioning incremental movement.

7. A tendency drive arrangement as in claim 6 wherein each of said one end is arcuate, having a center of curvature at said :pivot support means respectively and said vibratory means is located relative to the center of said disk the point of contact between said vibratory driving means and each of said pair forms a right angle.

8. A tendency drive arrangement for a mechanism required to provide continuous torque comprising:

a drive disk coupled to the mechanism; a curved drive shoe positioned to have one end engage a portion of the surface of said disk; means for pivotably supporting said shoe and being a loose fit pivot support means to allow outward motion of said one end relative to said disk; spring means coupled to said shoe to bias said one end thereof against said disk and in given tangential direction relative thereof, thereby to tend to rotate said disk in said given direction; and a vibratory driving means drivable to engage said shoe sequentially to counteract the spring bias and to move said one end thereof to a new position on said disk to the extent said disk has rotated since a last engagement of said driving means on said shoe.

References Cited by the Examiner UNITED STATES PATENTS 10/1934 Ervart 74-143 1/1942 Obszarny 74-443 

1. A TENDENCY DRIVE ARRANGEMENT COMPRISING: A DRIVE DISK; A PAIR OF ARCUATE DRIVE SHOES EACH POSITIONED TO PRODUCE SELECTIVE ROLLING ACTION AGAINST SAID DISK AND TO HAVE ONE END OF EACH ENGAGE A SEPARATE PORTION OF THE SURFACE OF SAID DISK; MEANS FOR PIVOTABLY SUPPORTING SAID PAIR; SPRING MEANS COUPLED BETWEEN SAID PAIR AT POINTS SPACED FROM SAID PIVOT SUPPORT MEANS TO BIAS SAID PAIR AGAINST SAID DISK AND IN A GIVEN TANGENTIAL DIRECTION RELATIVE THERETO, THEREBY TO TEND TO ROTATE SAID DISK IN SAID GIVEN DIRECTION; 